Electromagnetic bell



Nov. 23, 1937. J. |=v EBERT ELECTROMAGNETIC BELL Filed June 18, 1931 R Q m a m mx y 3% W n Patented Nov. 23, 1937 UNITED STATES PATENT OFFICE ELECTROMAGNETIC BELL Joseph F. Ebert, Engineering York, N. I,

Application June 18, 1931, Serial No. 545.355

1 Claim.

The present invention relates to electromagnetic bells of the single stroke type in which the energization of an operating solenoid causes a plunger or striker to hit a gong disposed in the path of movement of the upper end of the plunger, the plunger remaining in its striking position as long as the solenoid is energized.

The object of the invention is to provide an improved attachment for bells of the above indicated type whereby the bell may be readily converted into a recurrent stroke or vibrating bell, that is a bell in which the plunger will make separate strokes, uniformly spaced, as long as the solenoid remains energized. The attachment which constitutes the present invention consists of an improved circuit making and breaking device adapted to cooperate with the bell plunger, all of the parts being adapted to be applied to the magnetic frame of the bell as an assembly, as will hereinafter appear from the following description with reference to the accompanying drawing, in which:-

Fig. 1 is a transverse sectional view of an electromagnetic bell provided with a circuit con-- trolling attachment embodying the invention.

Fig. 2 is a rear elevation oi the magnetic frame of the hell with the circuit controlling attachment secured thereto.

Fig. 3 is a plan view of the attachment shown Fig. 2, removed from the bell. Fig. 4 is a fragmentary sectional view showing a portion of the parts of Fig. 1 in a diiferent position and on an enlarged scale.

Like reference characters refer to like parts in the different figures.

Referring to the drawing, the bell structure to which my improved circuit controlling attachment is applied consists of a magnetic yoke or frame I providing a recess 2, in which is received an operating solenoid 3. The solenoid 3 surrounds a tube 4 of insulating material received in 'alined openings I provided in the frame I, and a striker or plunger 8 is longitudinally movable in the tube 4 under the influence oi the solenoid 3.

Preferably the lower end of the tube 4 is closed by a suitable plug I, so as to maintain the plunger I in the position shown, with only the upper portion of the plunger extending within the solenoid, then assumed to be in a deenergized condition. A resonant gong I of any desired type is secured to the magnetic frame I by a bolt 9, the open rim of the gong 8 extending over the axis of the magnetic plunger 8. Consequently, when the solenoid l is energized from any suitable source 55 of electrical energy, the plunger 8 will be drawn up within the solenoid I, and a metal striking tip Ill at its upper end will hit the rim of the gong a single sharp blow. The plunger 6 will remain in its striking position as long as the solenoid 3 is continuously energized, and the object of the 6 present invention is to provide an attachment for a single stroke bell construction of the type above described, whereby the bell plunger is adapted to hit recurrent strokes on the gong 8 in response to continuous energization of the solenoid 3.

The attachment consists of a U-shaped bracket I I, the spaced legs of which provide flanges l2, l2 that are attached to the face of the magnetic frame I surrounding the coil recess 2 by means of screws ll so that the bracket may be readily 15 attached to or removed from the frame. As best shown in Fig. 1, the lower portion of the bracket II carries a series of plates ll of insulating material between which are clamped a pair of upwardly extending resilient contact fingers i5 and 20 i6, screws l'l serving to secure the assembled insulating plates II and contact fingers i5 and It to the bracket II, with finger l5 extending beyond finger ii.

In assembling the contact fingers l5 and it, the finger I6 is initially bent away from the finger it so as to yieldingly maintain contact tips lid and lid, respectively, carried by the fingers, in engagement. Consequently, the contact finger i5 is slightly deflected out of exact parallelism with a stifl stop arm ll extending between the fingers. The upper end of the arm It provides an opening I! see Fig. 4, through which the engaged contact tips Ito and lBa freely extend, so that both fingers Ii and i6 are adapted to be flexed independently of the arm Ill, as will hereinafter appear.

One terminal of the solenoid 3 is connected to the contact finger I! by means of a lead 20, while the other terminal thereof is connected to a terminal screw 2| provided by an insulating block 22 located in a junction box 23 of any desired type, upon which the bell frame I is mounted.

A second terminal screw It is connected by a lead 26 to the other contact arm It, so that with the contact tips lid. and I60 in engagement, the circuit between the solenoid 3 and the terminal screws 2i and 24 is complete. Consequently, energization of the terminal screws 2| and 24 in the junction box 23 from any suitable source of electrical energy, not shown, will cause energization of the solenoid 3.

As the plunger 8 is drawn upwardly within the solenoid l in response to energization thereof, one arm 28a of a lever pivoted at 21 is engaged to by the plunger 8 to turn the lever and move its other arm 28b into engagement with the upper end of the contact finger II which extends above the other finger l8. Preferably the pivot 21 for the lever is supported between spaced ears 28 provided by the bracket ll, so that the lever forms part of the bracket assembly. The lower end of the lever arm 28b carries an insulating tip 28 for engagement with the contact finger i5, and as best shown in Fig. 3, the outer end of the other lever arm 280; provides an open notch 30 adapted to, freely receive the striking tip l8 of the plunger. With this arrangement, the tip l8 passes through the notch 38 on its upward movement and the iever'arm 26a is not turned'until it is engaged by the shoulder in of the plunger 8 Just below the will It is evident from a consideration of Fig. 1 that the shoulder 60. of the plunger 8 will engage the lever arm 260. before the tip l8 strikes the gong 8, thereby turning the lever to cause the arm 28b to engage contact finger it. As the finger it moves away from the still stop arm l8, the other finger it follows it until a washer 8| carried by the finger it engages the arm l8. The washer BI is of greater diameter than the opening l8 in the arm l8, so that movement of the contact tip its is checked just as continued flexure of the finger Si by the lever arm 25b separates the contact tip l5a therefrom, as shown in Fig. 4.

Due to the fact that engagement between the contact tips I50. and lid is momentarily maintained after the finger l5 starts to move, the inertia of the upwardly moving plunger 8 causes it to complete its upward movement to strike the gong 8 a sharp blow just as the solenoid 3 is deenergized by separation of the contact tips I54: and IE0. As the plunger 6 drops upon deenergization of the solenoid 3, the lever arm 26b releases the deflected finger i5, whereupon the tip lBa reengages the tip I60. to reestablish the circuit of the solenoid 3. This reengagement of the tips I50. and ma is accompanied by a yielding of the finger i6 under the pressure of the finger l5, thereby eifectively preventing any rebound between the contact tips which might otherwise occur, were one of the fingers rigid.

Owing to the fact that the tip lid. reengages the tip I80. before the lever arm 2617 has actually released the end of the finger IS, the circuit of the solenoid 3 is reestablished slightly in advance of the arrival of the falling plunger 6 at the bottom of the tube 4, as shown in Fig. 1. Therefore, the magnetic frame is fully saturated by the time the plunger 6 reaches its lowest position. with the result that the plunger starts on another stroke without any appreciable time lag. Furthermore, the energization of the solenoid in advance of the arrival of the plunger to its lowermost position serves to cushion the downward movement of the plunger. This insertion has been made to indicate in the disclosure an advantage of applicants bell upon which claim was held allowable. On the next upward stroke of the plunger 8, the operation is the same. the circuit of the solenoid 8 being maintained through the yielding fingers i8 and I8 up to the point where the tip i8 is just about to strike the gong 8.

As a result of the above described functioning of the circuit controlling device, the bell is adapted to strike recurrent strokes on the gong 8 as long as the terminal screws II and 24 are energized, the strokes being clear and distinct, with uniform intervals therebetween. The simultaneous movement of both fingers i8 and II in response to turning of the lever arm 28b insures that the circuit of the solenoid will be maintained up to the striking of the gong and will be reestablished before the plunger has fallen all the way. This insures not only uniform timing of the signals, but also prevents the plunger from striking the gong lightly, or missing altogether, due to breaking the solenoid circuit prematurely. In other words, the tendency of the yieldable fingers l5 and II to maintain the solenoid circuit during flexure of the finger It by the lever arm 28b renders the timing of the device more uniform, in comparison with a circuit controlling device employing the usual fixed and movable contacts.

I claim:

In an electromagnetic bell,the combination with a magnetic frame carrying a solenoid, a magnetic plunger movable axially of the solenoid and a gong carried by said frame with its open rim extending in the path of movement of said plunger, of a circuit making and breaking device for controlling the energization of said solenoid comprising a pair of yieldable contacts normally in engagement to maintain the circuit of said solea rigid stop interposed between said contacts out of engagement therewith, and an actuating member responsive to movement of said plunger towards said gong for engaging the undeflected contact before said plunger strikes the gong and moving it away from the deflected contact, the initially deflected contact following the movement of the other contact by said actuating member to maintain the circuit of said solenoid until said contact strikes said step, after which further movement of the other contact by the actuating member serves to break the circuit of the solenoid just as said plunger strikes the gong, downward movement of said plunger following deenergization of the solenoid permitting re-engagement of said contacts, free of said stop, to re-energize said solenoid in advance of the arrival of said plunger in its lowermost position.

JOSEPH F. EBERT.

' noid, with one of said contacts initially deflected, 40

CERTIFICATE OF CORRECTION".

Patent No. 2,099,929. 7 November 23, 195?.

JOSEPH F. EBERT.

It is hereby certified that error appears inthe printed specification of the above numbered patent requiring correction as follows: Page 2, second column, lines 1, Zand}, strike out the words and period "This insertion has been made to indicate in the disclosure an advantage of applicant's bell upon which claimwas held allowable."'; andthat the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent office.

Signed and sealed this 1st day of February, A. D. 1938.

Henri Van Arsdale,

(Seal) Acting Commissioner of Patents. 

